Water-emulsifiable isocyanates for coatings having an improved gloss

ABSTRACT

The invention relates to new, water-emulsifiable isocyanates, to a process for preparing water-emulsifiable isocyanates, and to the use thereof.

The invention relates to new, water-emulsifiable isocyanates, to aprocess for preparing water-emulsifiable isocyanates, and to the usethereof.

Water-emulsifiable polyisocyanates are added as crosslinking agents toaqueous polymer dispersions and have been much described in theliterature. The emulsifiability in water is obtained by blending thepolyisocyanates with emulsifiers themselves obtained by reacting thepolyisocyanates with hydrophilic molecules.

Much in use as hydrophilic molecules are nonionic hydrophilic moleculessuch as polyalkylene oxide alcohols.

EP-A2 206 059 describes water-dispersible polyisocyanate preparationscomprising an aliphatic polyisocyanate and a reaction product of analiphatic polyisocyanate with a mono- or polyhydric, nonionicpolyalkylene ether alcohol, with at least one polyether chain having atleast 10 ethylene oxide units, as emulsifier. For suitablepolyisocyanates, extensive lists of polyisocyanates based on aliphaticand cycloaliphatic diisocyanates are reported, more preferablyisocyanurates and biurets based on 1,6-diisocyanatohexane (HDI) and/orisocyanurates based on1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI).

EP-A1 540 985 likewise describes polyisocyanate mixtures, but here thepolyether chains have an average of 5.0 to 9.9 ethylene oxide units.

EP-A2 486 881 describes nonaqueous aliphatic polyisocyanate preparationsfrom a list of aliphatic polyisocyanates and a quantity, ensuring thedispersibility of the aliphatic polyisocyanate, of a reaction product ofan aromatic or aliphatic diisocyanate and a monohydric or (lesspreferably) polyhydric polyalkylene ether alcohol having at least 8ethylene oxide units in the polyether chain. Monofunctional polyethyleneglycols exclusively are used in the examples. The reaction of thediisocyanates with the alcohols takes place in a ratio of 60 to 120 mol% in terms of OH groups relative to the NCO groups of the diisocyanate.The products obtained in this way then act as emulsifiers in the blendswith polyisocyanates.

WO 01/40347 describes water-dispersible polyisocyanate mixtures withpolyether chains containing an average of 5 to 33 ethylene oxide unitsand a defined fraction bonded via allophanate groups.

EP 959087 A1 describes water-emulsifiable, polyether-modifiedpolyisocyanate mixtures in which a high proportion of the polyethers isbonded to the polyisocyanate via allophanate groups.

A disadvantage of this is that the formation of allophanate groupsconsumes, by reaction, two equivalents of isocyanate groups per hydroxylgroup, and hence the NCO content of the product, measured relative tothe reactant, is sharply reduced.

WO 2009/156683 discloses mixtures of water-dispersible polyisocyanatessome of which carry ionic groups and some of which carry nonionicgroups.

DE-A1 199 58 170 describes polyether-modified, water-dispersiblepolyisocyanate mixtures which have been modified with monohydricpolyalkylene oxide polyether alcohols. Especially preferred arepolyisocyanates or polyisocyanate mixtures with isocyanurate structurebased on HDI, IPDI and/or 4,4′-diisocyanatodicyclohexylmethane.

DE-A1 198 22 890 describes aqueous, two-component polyurethane coatingsystems in which the curing component is prepared underallophanatization conditions from polyalkylene oxide polyether alcoholsand from allophatically and/or cycloaliphatically bonded isocyanategroups, preferably isocyanurate structures based on HDI, IPDI and/or4,4′-diisocyanatodicyclohexylmethane. The predominant bonding ofpolyether chains via allophanate groups is also known from DE-A1 198 47077.

A disadvantage of the polyisocyanate mixtures described is that theyfail to meet the requirements imposed on the gloss of the coatingsobtainable using them.

Water-emulsifiable isocyanates can be dissolved in organic solvents suchas carbonic esters or lactones, for example, for the purpose ofimproving their dispersibility, as described in EP-A 697 424.

WO 2004/22624 describes water-emulsifiable mixtures of polyisocyanatesbased on 1,6-hexamethylene diisocyanate with polyisocyanates based onisophorone diisocyanate, which exhibit not only high hardness but alsogood emulsifiability in water.

The drying properties of the coatings obtained with these coatingcompositions, however, are inadequate.

WO 2012/007431 describes high-functionality polyisocyanates which haveurethane groups, and which are obtainable by reaction of at least onepolyfunctional alcohol with at least one polyisocyanate in a molar ratioof NCO groups to OH groups of at least 3:1.

A disadvantage is that these high-functionality polyisocyanates havingurethane groups are not water-emulsifiable.

WO 2011/124710 A describes coating compositions comprisinghydroxyl-containing fatty acid glycerides, polyisocyanates, and binders.

The resulting coatings exhibit self-healing effects on heating.

A disadvantage is that the coating compositions, which represent athree-component system, are not water-emulsifiable.

The unpublished European patent application 12186603.2, filed Sep. 28,2012, and the US provisional application filed on the same date, withthe file reference 61/706,806, disclose improving the gloss ofwater-emulsifiable polyisocyanates through incorporation of polyolshaving a functionality of 2 to 4 and a number-average molar weight of atleast 92 to 1500 g/mol, these polyols preferably being products ofesterification of fatty acids with polyalcohols.

A disadvantage is that the esterification produces product mixtureswhich do not have a defined functionality but instead always have only afunctionality with a scattering.

The following qualities are demanded by the user of a water-emulsifiableisocyanate:

1. The isocyanate is to be easy to emulsify; the mandatory use ofdemanding apparatus such as high-shear stirring elements, for example,is unwanted.2. The emulsion is to be fine, since otherwise disruptions to the gloss,for example, or instances of clouding, may occur.3. In the case of coatings, a high gloss is wanted.4. The viscosity of the water-emulsifiable isocyanate is to be not toohigh.

It was an object of the present invention to provide a process forpreparing water-emulsifiable polyisocyanates which exhibit goodemulsifiability properties, have a viscosity at 23° C. of not more than15 Pas, and can be used to obtain coatings with high gloss.

The object has been achieved by means of water-emulsifiablepolyisocyanates comprising

-   (A) at least one polyisocyanate based on at least one    (cyclo)aliphatic diisocyanate,-   (B) at least one compound (B) having at least two, preferably two to    four, more preferably two to three, and very preferably precisely    two isocyanate-reactive groups, comprising at least one group    selected from the group consisting of thioether groups (—S—),    selanyl groups (—Se—), sulfoxide groups (—S(═O)—), and sulfone    groups (—S(═O)₂—),-   (C) at least one compound having at least one isocyanate-reactive    group and at least one dispersive group, and-   (D) optionally solvent(s), where    -   the ratio of NCO groups in (A) to isocyanate-reactive groups        in (B) and (C) is from at least 5:1 to 100:1,    -   the ethylene oxide group content, calculated as 44 g/mol, based        on the sum of (A), (B), and (C), is at least 12 wt. %,        preferably at least 14, more preferably at least 15 wt. %,    -   the amount of component (C), based on (A), is at least 5 and up        to 25 wt. %, and    -   the viscosity at 23° C. to DIN EN ISO 3219/A.3 (October 1994) in        a cone/plate system with a shear rate of 1000 s⁻¹ is from 2500        mPas to 12 000 mPas.

These polyisocyanates display easy emulsifiability, lead to a stable andfine emulsion, and can be used to obtain coatings which exhibit highgloss. Component (B) has a defined functionality without variance andthus permits the construction of defined structures in thepolyisocyanate.

The polyisocyanates (A) are oligomers of aliphatic or cycloaliphaticdiisocyanates, dubbed (cyclo)aliphatic for short in this specification.

The NCO functionality of the polyisocyanates (A) is generally at least1.8 and can be up to 8, preferably 1.8 to 5, and more preferably 2 to 4.

Polyisocyanates contemplated are polyisocyanates having isocyanurategroups, polyisocyanates having uretdione groups, polyisocyanates havingbiuret groups, polyisocyanates having urethane or allophanate groups,polyisocyanates comprising oxadiazinetrione groups oriminooxadiazinedione groups, or uretonimine-modified polyisocyanatesbased on linear or branched C₄-C₂₀-alkylene diisocyanates orcycloaliphatic diisocyanates having a total of 6 to 20 C atoms, ormixtures thereof.

The (cyclo)aliphatic diisocyanates are preferably isocyanates having 4to 20 C atoms. Examples of typical diisocyanates are aliphaticdiisocyanates such as tetramethylene diisocyanate, hexamethylenediisocyanate (1,6-diisocyanatohexane), octamethylene diisocyanate,decamethylene diisocyanate, dodecamethylene diisocyanate,tetradecamethylene diisocyanate, derivatives of lysine diisocyanate,trimethylhexane diisocyanate or tetramethylhexane diisocyanate,cycloaliphatic diisocyanates such as 1,4-, 1,3- or1,2-diisocyanatocyclohexane, 4,4′- or2,4′-di(isocyanatocyclohexyl)methane,1-isocyanato-3,3,5-trimethyl-5-(isocyanatomethyl)cyclohexane (isophoronediisocyanate), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane, or 2,4- or2,6-diisocyanato-1-methylcyclohexane, and also 3 (or 4),8 (or9)-bis(isocyanatomethyl)tricyclo[5.2.1.0^(2,6)]decane isomer mixtures.Mixtures of said diisocyanates may also be present.

The diisocyanates which can be used preferably have an isocyanate groupcontent (calculated as NCO, molecular weight=42 g/mol) of 10 to 60 wt.%, based on the diisocyanate (mixture), preferably 15 to 60 wt. %, andmore preferably 20 to 55 wt. %.

Preference is given to aliphatic and/or cycloaliphatic—referred tocollectively for the purposes of this specification as(cyclo)aliphatic—diisocyanates and polyisocyanates, examples being theabovementioned aliphatic and cycloaliphatic diisocyanates, or mixturesthereof.

Particular preference is given to hexamethylene diisocyanate,1,3-bis(isocyanatomethyl)-cyclohexane, isophorone diisocyanate, and4,4′- or 2,4′-di(isocyanatocyclohexyl)methane, very particularpreference to isophorone diisocyanate and hexamethylene diisocyanate,and especial preference to hexamethylene diisocyanate.

Isophorone diisocyanate is usually in the form of a mixture,specifically a mixture of the cis and trans isomers, generally in aratio of about 60:40 to 80:20 (w/w), preferably in a ratio of about70:30 to 75:25, and more preferably in a ratio of about 75:25.

Dicyclohexylmethane 4,4′-diisocyanate may likewise be in the form of amixture of the different cis and trans isomers.

Cycloaliphatic isocyanates are those which comprise at least onecycloaliphatic ring system.

Aliphatic isocyanates are those which comprise exclusively linear orbranched chains, in other words acyclic compounds.

For the present invention it is possible to use not only those di- andpolyisocyanates obtained by phosgenating the corresponding amines butalso those prepared without the use of phosgene, i.e., by phosgene-freeprocesses. According to EP-A-0 126 299 (USP 4 596 678), EP-A-126 300(USP 4 596 679), and EP-A-355 443 (USP 5 087 739), for example,(cyclo)aliphatic diisocyanates, such as 1,6-hexamethylene diisocyanate(HDI), isomeric aliphatic diisocyanates having 6 carbon atoms in thealkylene radical, 4,4′- or 2,4′-di(isocyanatocyclohexyl)methane, and1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophoronediisocyanate or IPDI), for example, can be prepared by reacting the(cyclo)aliphatic diamines with, for example, urea and alcohols to give(cyclo)aliphatic biscarbamic esters and subjecting said esters tothermal cleavage into the corresponding diisocyanates and alcohols. Thesynthesis takes place usually continuously in a circulation process andin the presence, optionally, of N-unsubstituted carbamic esters, dialkylcarbonates, and other by-products recycled from the reaction process.Di- or polyisocyanates obtained in this way generally have a very low oreven unmeasurable fraction of chlorinated compounds, leading tofavorable color numbers in the products.

In one embodiment of the present invention the di- and polyisocyanates(A) have a total hydrolyzable chlorine content of less than 200 ppm,preferably of less than 120 ppm, more preferably less than 80 ppm, verypreferably less than 50 ppm, in particular less than 15 ppm, andespecially less than 10 ppm. This can be measured by means, for example,of ASTM specification D4663-98. Of course, though, di- andpolyisocyanates (A) having a higher chlorine content can also be used.

Further noteworthy are

-   1) Polyisocyanates having isocyanurate groups and derived from    aliphatic and/or cycloaliphatic diisocyanates. Particular preference    is given in this context to the corresponding aliphatic and/or    cycloaliphatic isocyanatoisocyanurates and in particular to those    based on hexamethylene diisocyanate and isophorone diisocyanate. The    isocyanurates present are, in particular, tris-isocyanatoalkyl    and/or tris-isocyanatocycloalkyl isocyanurates, which constitute    cyclic trimers of the diisocyanates, or are mixtures with their    higher homologs having more than one isocyanurate ring. The    isocyanatoisocyanurates generally have an NCO content of 10 to 30    wt. %, in particular 15 to 25 wt. %, and an average NCO    functionality of 2.6 to 8.-   2) Uretdione diisocyanates with aliphatically and/or    cycloaliphatically bonded isocyanate groups, preferably    aliphatically and/or cycloaliphatically bonded, and in particular    those derived from hexamethylene diisocyanate or isophorone    diisocyanate. Uretdione diisocyanates are cyclic dimerization    products of diisocyanates. The uretdione diisocyanates can be used    as a sole component or in a mixture with other polyisocyanates,    particularly those specified under 1).-   3) Polyisocyanates having biuret groups and having    cycloaliphatically or aliphatically bonded, preferably    cycloaliphatically or aliphatically bonded, isocyanate groups,    especially tris(6-isocyanatohexyl)biuret or its mixtures with its    higher homologs. These polyisocyanates having biuret groups    generally have an NCO content of 18 to 22 wt. % and an average NCO    functionality of 2.8 to 4.5.-   4) Polyisocyanates having urethane and/or allophanate groups and    having aliphatically or cycloaliphatically bonded, preferably    aliphatically or cycloaliphatically bonded, isocyanate groups, such    as may be obtained, for example, by reacting excess amounts of    hexamethylene diisocyanate or of isophorone diisocyanate with mono-    or polyhydric alcohols such as, for example, methanol, ethanol,    isopropanol, n-propanol, n-butanol, isobutanol, sec-butanol,    tert-butanol, n-hexanol, n-heptanol, n-octanol, n-decanol,    n-dodecanol (lauryl alcohol), 2-ethyihexanol, n-pentanol, stearyl    alcohol, cetyl alcohol, lauryl alcohol, ethylene glycol monomethyl    ether, ethylene glycol monoethyl ether, 1,3-propanediol monomethyl    ether, cyclopentanol, cyclohexanol, cyclooctanol, cyclododecanol,    trimethylolpropane, neopentyl glycol, pentaerythritol,    1,4-butanediol, 1,6-hexanediol, 1,3-propanediol,    2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol, ethylene glycol,    diethylene glycol, triethylene glycol, tetraethylene glycol,    pentaethylene glycol, glycerol, 1,2-dihydroxypropane,    2,2-dimethyl-1,2-ethanediol, 1,2-butanediol, 1,4-butanediol,    3-methylpentane-1,5-diol, 2-ethylhexane-1,3-diol,    2,4-diethyloctane-1,3-diol, hydroxypivalic acid neopentyl glycol    ester, ditrimethylolpropane, dipentaerythritol,    2,2-bis(4-hydroxycyclohexyl)propane, 1,1-, 1,2-, 1,3-, and    1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclohexanediol or    mixtures thereof. These polyisocyanates having urethane and/or    allophanate groups generally have an NCO content of 12 to 20 wt %    and an average NCO functionality of 2.5 to 4.5.-   5) Polyisocyanates comprising oxadiazinetrione groups, derived    preferably from hexamethylene diisocyanate or isophorone    diisocyanate. Polyisocyanates of this kind comprising    oxadiazinetrione groups are accessible from diisocyanate and carbon    dioxide.-   6) Polyisocyanates comprising iminooxadiazinedione groups, derived    preferably from hexamethylene diisocyanate or isophorone    diisocyanate. Polyisocyanates of this kind comprising    iminooxadiazinedione groups are preparable from diisocyanates by    means of specific catalysts.-   7) Uretonimine-modified polyisocyanates.-   8) Carbodiimide-modified polyisocyanates.-   9) Hyperbranched polyisocyanates, of the kind known for example from    DE-A1 10013186 or DE-A1 10013187.-   10) Polyurethane-polyisocyanate prepolymers, from di- and/or    polyisocyanates with alcohols.-   11) Polyurea-polyisocyanate prepolymers.

Polyisocyanates 1) to 11) may be used in a mixture, including optionallyin a mixture with diisocyanates.

The polyisocyanates (A) may also be present at least partly in blockedform.

Groups suitable for the blocking of isocyanates are described in D. A.Wicks, Z. W. Wicks, Progress in Organic Coatings, 36, 148-172 (1999),41, 1-83 (2001) and also 43, 131-140 (2001).

This is especially preferred when the coating compositions of theinvention are to be used in one-component form.

Preferred compounds (A) are the urethanes, biurets, and isocyanurates,more preferably the isocyanurates, of 1,6-hexamethylene diisocyanate(HDI) or 1-isocyanato-3-isocyanato-methyl-3,5,5-trimethylcyclohexane,very preferably of 1,6-hexamethylene diisocyanate.

As an inevitable result of their preparation, polyisocyanates (A) maystill have a small fraction of the parent monomeric diisocyanate—forexample, up to 5 wt. %, more preferably up to 3 wt %, very preferably upto 2, more particularly up to 1, especially up to 0.5, and even up to0.25 wt. %.

The compound (B) comprises at least one compound having at least two,preferably two to four, more preferably two to three, and verypreferably precisely two isocyanate-reactive groups, comprising at leastone group selected from the group consisting of thioether groups (—S—),selanyl groups (—Se—), sulfoxide groups (—S(═O)—), and sulfone groups(—S(═O)₂—).

Examples of isocyanate-reactive groups in compound (B) are —OH, —SH,—SeH, —NH₂, or —NHR⁸, in which R⁸ may be hydrogen, methyl, ethyl,isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, or tert-butyl. Theisocyanate-reactive groups in compound (B) are preferably —OH, —SH, or—NHR⁸, more preferably —OH or —SH, and very preferably —OH.

The compounds (B) in accordance with the invention have at least one,for example one to four, preferably one to three, more preferably one totwo, and very preferably precisely one thioether group (—S—) or selanylgroup (—Se—) or oxidation products thereof, particularly sulfoxidegroups (—S(═O)—) or sulfone groups (—S(═O)₂—).

A thioether group in the sense of the present specification means amoiety —S— which is substituted on both sides by (cyclo)aliphatic oraromatic carbons, preferably by (cyclo)aliphatic and more preferablyaliphatic carbon atoms. By “(cyclo)aliphatic or aromatic carbon” ismeant a carbon atom which is part of a (cyclo)aliphatic or aromaticradical, which may in turn itself be substituted by isocyanate-reactivegroups. In one preferred embodiment both (cyclo)aliphatic or aromaticradicals are substituted by precisely one isocyanate-reactive group.Analogous definitions apply in respect of selanyl groups (—Se—),sulfoxide groups (—S(═O)—), and sulfone groups (—S(═O)₂—).

In one preferred embodiment component (B) is selected from the groupconsisting of compounds of the formula

in which

R⁴ and R⁵ independently of one another are each C₁-C₁₈ alkylene,or—optionally interrupted by one or more oxygen atoms and/or sulfuratoms —C₂-C₁₈ alkylene, C₆-C₁₂ arylene, or C₅-C₁₂ cycloalkyl, it beingpossible for each of the stated radicals to be substituted by functionalgroups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/orheterocycles.

Preferably R⁴ and R⁵ independently of one another are each C₁-C₁₈alkylene, C₆-C₁₂ arylene, or C₅-C₁₂ cycloalkyl, and more preferablyindependently of one another are each C₁-C₁₈ alkylene, and moreparticularly C₂-C₆ alkylene, the stated radicals being able to besubstituted in each case by functional groups, aryl, alkyl, aryloxy,alkyloxy, halogen, heteroatoms and/or heterocycles, but with particularpreference being unsubstituted.

More preferably R⁴ and R⁵ independently of one another are selected fromthe group consisting of 1,2-ethylene, 1,2-propylene, 1,3-propylene,1,4-butylene, 1,5-pentylene, 1,6-hexylene, 2-methyl-1,3-propylene,2-ethyl-1,3-propylene, 2,2-dimethyl-1,3-propylene,2,2-dimethyl-1,4-butylene, 3-oxa-1,5-pentylene, 3,6-dioxa-1,8-octylene,3,6,9-trioxa-1,11-undecylene, 1,1-, 1,2-, 1,3- or 1,4-cyclohexylene,1,2- or 1,3-cyclopentylene, 1,2-, 1,3-, or 1,4-phenylene, and4,4′-biphenylene. Very preferably R⁴ and R⁵ independently of one anotherare selected from the group consisting of 1,2-ethylene, 1,2-propylene,1,3-propylene, 3-oxa-1,5-pentylene, and 1,4-phenylene. More particularlyR⁴ and R⁵ independently of one another are 1,2-ethylene, 1,2-propylene,or 1,3-propylene, and especially are 1,2-ethylene.

In one preferred embodiment R⁴ and R⁵ are each identical.

Among the compounds (B1) to (B4), the compounds (B1) are preferred.

Component (B) is preferably 3-thiapentane-1,5-diol (thiodiglycol),1,5-dimethyl-3-thiapentane-1,5-diol, 1-methyl-3-thiahexane-1,6-diol,4-thiaheptane-1,7-diol, 4,4′-thiobis(6-tert-butyl-m-cresol), and4,4′-dihydroxydiphenyl sulfide, more preferably 3-thiapentane-1,5-diol.

The amount of component (B) in the water-emulsifiable polyisocyanate ofthe invention is generally 0.5 to 15 wt. %, based on the sum of (A),(B), and (C), preferably 1 to 10 wt. %, more preferably 1.2 to 7, andvery preferably 1.5 to 5 wt. %.

Component (C) comprises at least one, for example one to three,preferably one to two, and more preferably precisely one compound havingat least one, preferably one or two, and more preferably precisely oneisocyanate-reactive group and at least one, preferably precisely one,dispersive group.

The components in question may preferably be compounds (C1) or (C2).

Such compounds (C1) are represented, for example, by the general formula

RG-R⁶-DG

in whichRG is at least one isocyanate-reactive group,DG is at least one dispersive group, andR⁶ is an aliphatic, cycloaliphatic, or aromatic radical comprising 1 to20 carbon atoms.

Examples of RG are —OH, —SH, —NH₂, or —NHR⁷, in which R¹ may behydrogen, methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl,sec-butyl, or tert-butyl.

DG may be alternatively ionic, as for example anionic or cationic, ornonionic, preferably anionic or nonionic, and more preferably nonionic.

In the case of anionic groups, examples of DG are —COOH, —SO₃H, —OPO₃H,or —POSH, and also anionic forms thereof, which may be associated withany desired counterion, examples being Li+, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺,Ba²⁺, ammonium, methylammonium, dimethylammonium, trimethylammonium,ethylammonium, diethylammonium, triethylammonium, tributylammonium,diisopropylethylammonium, benzyldimethylammonium, piperidinium,piperazinium, N,N′-dimethylpiperazinium, dimethylcyclohexylammonium,methyldicyclohexylammonium, morpholinium, or pyridinium, preferably Li⁺,Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Ba²⁺, ammonium, methylammonium,dimethylammonium, trimethylammonium, ethylammonium, diethylammonium,triethylammonium, tributylammonium, diisopropylethylammonium,benzyldimethylammonium, piperidinium, piperazinium,N,N′-dimethylpiperazinium, dimethylcyclohexylammonium,methyldicyclohexylammonium, morpholinium, or pyridinium.

R⁶ may for example be methylene, 1,2-ethylene, 1,2-propylene,1,3-propylene, 1,2-butylene, 1,4-butylene, 1,3-butylene, 1,6-hexylene,1,8-octylene, 1,12-dodecylene, 1,2-phenylene, 1,3-phenylene,1,4-phenylene, 1,2-naphthylene, 1,3-naphthylene, 1,4-naphthylene,1,6-naphthylene, 1,2-cyclopentylene, 1,3-cyclopentylene,1,2-cyclohexylene, 1,3-cyclohexylene, or 1,4-cyclohexylene.

An anionic component (C1) of this kind is preferably, for example,mercaptoacetic acid, mercaptopropionic acid, thiolactic acid,mercaptosuccinic acid, glycine, iminodiacetic acid, sarcosine, alanine,β-alanine, leucine, isoleucine, aminobutyric acid, hydroxyacetic acid,hydroxypivalic acid, lactic acid, hydroxysuccinic acid, hydroxydecanoicacid, dimethylolpropionic acid, dimethylolbutyric acid,ethylenediaminetriacetic acid, hydroxydodecanoic acid,hydroxyhexadecanoic acid, 12-hydroxystearic acid, aminobenzenesulfonicacids substituted on the ring by alkyl, as described in WO 2009/010469,aminonaphthalenecarboxylic acid, hydroxyethanesulfonic acid,hydroxypropanesulfonic acid, mercaptoethanesulfonic acid,mercaptopropanesulfonic acid, aminomethanesulfonic acid, taurine,aminopropanesulfonic acid, N-alkyl-, -cycloalkyl-, or -aryl-substitutedaminomethanesulfonic acids or aminopropanesulfonic acid, and also thealkali metal, alkaline earth metal, or ammonium salts thereof, and morepreferably the stated monohydroxycarboxylic and -sulfonic acids and alsomonoaminocarboxylic and -sulfonic acids, more preferably4-aminotoluene-2-sulfonic acid, N-cyclohexyl-2-aminoethanesulfonic acid,and N-cyclohexylamino-3-propanesulfonic acid.

For the preparation the aforementioned acids, if not already salts, arepartly or fully neutralized, preferably with alkali metal salts oramines, preferably tertiary amines.

Compounds (C1) having cationic groups DG may comprise at least one groupthat is reactive toward isocyanate groups, and at least one hydrophilicgroup which is cationic or can be converted into a cationic group, andare, for example, compounds of the kind described in EP-A1 582 166,particularly from page 5, line 42 to page 8, line 22 and moreparticularly from page 9, line 19 to page 15, line 34 therein, or inEP-A1 531 820, particularly from page 3, line 21 to page 4, line 57therein, or in DE-A1 42 03 510, particularly from page 3, line 49 topage 5, line 35 therein. For the purposes of the present disclosure,these specifications are hereby incorporated expressly by reference.

Compounds (C1) may comprise at least one, preferably precisely one groupthat is reactive toward isocyanate groups, and at least one, preferablyprecisely one hydrophilic group which is anionic or can be convertedinto an anionic group, and are, for example, compounds as described inEP-A1 703 255, particularly from page 3, line 54 to page 4, line 38therein, in DE-A1 197 24 199, particularly from page 3, line 4 to line30 therein, in DE-A1 40 10 783, particularly from column 3, lines 3 to40 therein, in DE-A1 41 13 160, particularly from column 3, line 63 tocolumn 4, line 4 therein, in WO 2009/010469 A1, particularly from page8, line 41 to page 11, line 17 therein, and in EP-A2 548 669,particularly from page 4, line 50 to page 5, line 6 therein. For thepurposes of the present disclosure, these specifications are herebyincorporated expressly by reference.

Preferred compounds (C1) are those in which DG is a nonionic group.These preferred compounds (C1) comprise at least one, preferablyprecisely one group that is reactive toward isocyanate groups, and atleast one, preferably precisely one nonionic hydrophilic group.

This hydrophilic group comprises at least one monoalcohol having atleast 7, preferably at least 10, ethylene oxide groups.

Generally speaking, component (C1) comprises not more than 30 ethyleneoxide groups, preferably not more than 25, and more preferably not morethan 20 ethylene oxide groups.

Ethylene oxide groups in this context are groups —CH₂—CH₂—O— which areinstalled in repetition in component (C1).

Suitable monools whose ethoxylated products can be used as components(C1) include methanol, ethanol, isopropanol, n-propanol, n-butanol,isobutanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol, n-octanol,n-decanol, n-dodecanol (lauryl alcohol), 2-ethylhexanol, cyclopentanol,cyclohexanol, cyclooctanol, and cyclododecanol. The aforementioned C₁ toC₄ alkanols are preferred, and methanol is particularly preferred.

Particularly preferred compounds (C1) are polyalkylene oxide polyetheralcohols obtainable by alkoxylating monohydroxy compounds of the generalformula

R¹—O—H

or secondary monoamines of the general formula

R²R³N—H,

in which

R¹, R², and R³ independently of one another are each C₁-C₁₈ alkyl,C₂-C₁₈ alkyl uninterrupted or interrupted by one or more oxygen and/orsulfur atoms, or are C₆-C₁₂ aryl, C₅-C₁₂ cycloalkyl or a five- orsix-membered heterocycle having oxygen, nitrogen and/or sulfur atoms, orR² and R³ together form an unsaturated, saturated or aromatic ringuninterrupted or interrupted by one or more oxygen and/or sulfur atoms,it being possible for the radicals mentioned each to be substituted byfunctional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatomsand/or heterocycles.

Preferably R¹ is C₁ to C₄ alkyl, i.e., methyl, ethyl, isopropyl,n-propyl, n-butyl, isobutyl, sec-butyl or tert-butyl; very preferably R¹is methyl.

Examples of suitable monofunctional starter molecules may be saturatedmonoalcohols such as methanol, ethanol, n-propanol, isopropanol,n-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols,octanols and nonanols, n-decanol, n-dodecanol, n-tetradecanol,n-hexadecanol, n-octadecanol, cyclohexanol, cyclopentanol, the isomericmethylcyclohexanols or hydroxymethylcyclohexane,3-ethyl-3-hydroxymethyloxetane, or tetrahydrofurfuryl alcohol;unsaturated alcohols such as allyl alcohol, 1,1-dimethylallylalcohol oroleyl alcohol, aromatic alcohols such as phenol, the isomeric cresols ormethoxyphenols, araliphatic alcohols such as benzyl alcohol, anisylalcohol or cinnamyl alcohol; secondary monoamines such as dimethylamine,diethylamine, dipropylamine, diisopropylamine, di-n-butylamine,diisobutylamine, bis(2-ethylhexyl)amine, N-methyl- andN-ethylcyclohexylamine or dicyclohexylamine, heterocyclic secondaryamines such as morpholine, pyrrolidine, piperidine or 1H-pyrazole, andalso amino alcohols such as 2-dimethylaminoethanol,2-diethylaminoethanol, 2-diisopropylaminoethanol, 2-dibutylaminoethanol,3-(dimethylamino)-1-propanol or 1-(dimethylamino)-2-propanol.

Preferred compounds (C1) are polyether alcohols based on polyalkyleneoxide polyether alcohols prepared using saturated aliphatic orcycloaliphatic alcohols of the abovementioned type as initiatormolecules. Very particular preference is given to those based onpolyalkylene oxide polyether alcohols prepared using saturated aliphaticalcohols having 1 to 4 carbon atoms in the alkyl radical. Polyalkyleneoxide polyether alcohols prepared starting from methanol are especiallypreferred.

The monohydric polyalkylene oxide polyether alcohols have on averagegenerally from 7 to 30, preferably from 7 to 25, more preferably from 7to 20, very preferably from 10 to 20 ethylene oxide units per molecule.

Preferred polyether alcohols (C1) are, therefore, compounds of theformula

R¹—O—[—X_(i)—]_(k)—H

in which

R¹ is as defined above,

k is an integer from 7 to 30, more preferably 7 to 25, and in particular10 to 20, and each X_(i) for i=1 to k is —CH₂—CH₂—O—.

The polyether alcohols may further comprise, as hydrophilic synthesiscomponents, minor amounts of other isocyanate-reactive compounds withanionic or cationic groups—for example, with carboxylate, sulfonate orammonium groups. This, however, is less preferred.

Compounds (C2) are phosphoric esters of the formulae (Ia) or (Ib) ormixtures thereof:

in which

R¹⁰ and R¹¹ independently of one another may be alkyl, preferably C₁ toC₂₀ alkyl, cycloalkyl, preferably C4 to C8 cycloalkyl, aryl, preferablyC₆ to C₁₀ aryl, or aralkyl, preferably C7 to C15 aralkyl.

The groups R¹⁰ and R¹¹ may also be interrupted by heteroatoms such as O,N, or S, but are not to carry any isocyanate-reactive groups such as NH,OH, SH, and COOH, for example.

Preferred compounds (C2) are monomethyl phosphate, dimethyl phosphate,monoethyl phosphate, diethyl phosphate, mono-n-butyl phosphate,di-n-butyl phosphate, mono-2-ethylhexyl phosphate, di-2-ethylhexylphosphate, and mixtures thereof.

More preferably the radicals R¹⁰ and R¹¹ derive from fatty acid alcoholsor alkoxylated fatty acid alcohols, and are, for example, radicals ofthe general formula (II)

R¹²—O—[—X_(i)—]_(n)—

in whichR¹² is C₁ to C₂₀ alkyl,n is 0 (zero) or a positive integer from 1 to 20, andeach X, for i=1 to n, independently of one another, may be selected fromthe group consisting of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, and—CH(CH₃)—CH₂—O—.

Where the compounds of the formulae (la) and (Ib) are used as mixtures,they are employed preferably in a molar ratio between monoester (Ib) anddiester (Ia) of 5:95 to 95:5, preferably of 20:80 to 80:20, morepreferably of 30:70 to 70:30, and more particularly of 33:67 to 67:33.

It is thought that in reaction of isocyanates with phosphoric esters ofthis kind, in each case one of the hydroxy groups of the phosphoricesters reacts with the NCO groups of the isocyanate in an additionreaction, with formation of a covalent bond.

Of the compounds (C1) and (C2), the compounds (C1) are preferred.

For preparing the water-emulsifiable polyisocyanates, at least part, andpreferably the whole amount, of starting component (A) is reacted attemperatures of from 40 to 180° C., preferably 50 to 150° C., with atleast part, preferably the total amount, of the compound (B) and/or (C).

The reaction takes place with observance of an equivalents ratio of NCOgroups to isocyanate-reactive groups (total in (B) and (C)) of at least5:1, preferably at least 7:1, and more preferably at least 10:1, andalso up to 100:1, preferably up to 50:1, more preferably up to 30:1,very preferably up to 25:1, and more particularly up to 18:1.

It is also possible, although less preferable, first to react startingcomponent (A) at least partly with (B) and only subsequently with (C),or, conversely, first to react starting component (A) at least partlywith (C) and only subsequently with (B). Preference, however, is givento the simultaneous reaction of (A), (B), and (C).

The reaction mixture is reacted with component (C) in an amount suchthat the end product has an ethylene oxide group content, calculated as44 g/mol, based on the sum of components (A), (B), and (C), of at least12 wt. %, preferably at least 14 and more preferably at least 15 wt. %.The ethylene oxide group content generally does not exceed 25 wt. %,preferably not more than 23, more preferably not more than 20 wt. %.

The reaction time is generally 10 min to 5 hours, preferably 15 min to 4hours, more preferably 20 to 180 min, and very preferably 30 to 120 min.

In order to accelerate the reaction it is possible optionally to usesuitable catalysts.

The reaction is preferably accelerated by addition of a suitablecatalyst. Such catalysts are known from the literature, as for examplefrom G. Oertel (ed.), Polyurethane, 3rd edition, 1993, Carl HanserVerlag, Munich-Vienna, pages 104 to 110, section 3.4.1. “Katalysatoren”;preferred are organic amines, especially tertiary aliphatic,cycloaliphatic, or aromatic amines, Brønsted acids and/or Lewis-acidicorganometallic compounds; Lewis-acidic organometallic compounds areparticularly preferred.

Further metal catalysts are described by Blank et al. in Progress inOrganic Coatings, 1999, Vol. 35, pages 19-29.

Suitable catalysts are, in particular, zinc compounds, such as zinc(II)stearate, zinc(II) n-octanoate, zinc(II) 2-ethyl-1-hexanoate, zinc(II)naphthenate or zinc(II) acetylacetonate, tin compounds, such as tin(II)n-octanoate, tin(II) 2-ethyl-1-hexanoate, tin(II) laurate, dibutyltinoxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltindilaurate, dibutyltin dimaleate or dioctyltin diacetate, aluminumtri(acetoacetate), iron(III) chloride, potassium octoate, manganesecompounds, cobalt compounds, bismuth compounds, Zn(II) compounds, Zr(IV)compounds or nickel compounds, and strong acids, such as trifluoroaceticacid, sulfuric acid, hydrogen chloride, hydrogen bromide, phosphoricacid or perchioric acid, for example, or any desired mixtures of thesecatalysts.

Preferred catalysts for the process of the invention are zinc compoundsof the abovementioned type. Very particular preference is given to usingzinc(II) n-octanoate, zinc(II) 2-ethyl-1-hexanoate and/or zinc(II)stearate.

Also possible are metal complexes such as acetylacetonates of iron, oftitanium, of aluminum, of zirconium, of manganese, of nickel, of zinc,and of cobalt.

Tin-free and zinc-free alternatives used include, compounds ofzirconium, of bismuth, of titanium, and of aluminum. Examples of thesecompounds are zirconium tetraacetylacetonate (e.g., K-KAT® 4205 fromKing Industries); zirconium dionate (e.g., K-KAT® XC-9213; XC-A 209 andXC-6212 from King Industries); and aluminum dionate (e.g., K-KAT® 5218from King Industries).

Zinc compounds and bismuth compounds contemplated in this contextinclude those in which the following anions are employed: F—, Cl—, ClO—,ClO₃—, ClO₄—, Br—, I—, IO₃—, CN—, OCN—, NO₂—, NO₃—, HCO₃—, CO₃ ²—, S²—,SH—, HSO₃—, SO₃ ²—, HSO₄—, SO₄ ²—, S₂O₂ ²—, S₂O₄ ²—, S₂O₅ ²—, S₂O₆ ²—,S₂O₇ ²—, S₂O₆ ²—, H₂PO₂—, H₂PO₄—, HPO₄ ²—, PO₄ ³—, P₂O₇ ⁴—,(OC_(n)H_(2n+1))—(C_(n)H_(2n−1)O₂)—, (C_(n)H_(2n−3)O₂)— and(C_(n+1)H²⁻²O₄)²—, n standing for the numbers 1 to 20. Preference hereis given to the carboxylates in which the anion conforms to the formulae(C_(n)H_(2n−1)O₂)— and (C_(n+1)H_(2n−2)O₄)²— with n being 1 to 20.Particularly preferred compounds have monocarboxylate anions of thegeneral formula (C_(n)H_(2n−1)O₂)— where n stands for the numbers 1 to20. Particularly noteworthy in this context are formate, acetate,propionate, hexanoate, neodecanoate, and 2-ethylhexanoate.

Among the zinc catalysts the zinc carboxylates are preferred, morepreferably those of carboxylic acids which have at least two and up totwelve carbon atoms, more particularly zinc(II) diacetate or zinc(II)dioctoate or zinc(II) neodecanoate. Commercial catalysts are, forexample, Borchi® Kat 22 from OMG Borchers GmbH, Langenfeld, Germany.

Of the bismuth catalysts the bismuth carboxylates are preferred, morepreferably those of carboxylic acids which have at least two and up totwelve carbon atoms, more particularly bismuth octoates,2-ethylhexanoates, neodecanoates, or pivalates; examples are K-KAT 348,XC-B221; XC-C₂₂₇, XC 8203, and XK-601 from King Industries, TIB KAT 716,716LA, 716XLA, 718, 720, 789, from TIB Chemicals, and those fromShepherd Lausanne, and also, for example, Borchi® Kat 24; 315; 320 fromOMG Borchers GmbH, Langenfeld, Germany.

The catalysts in question may also be mixtures of different metals, suchas in Borchi® Kat 0245 from OMG Borchers GmbH, Langenfeld, Germany, forexample.

Among the titanium compounds the titanium tetraalkoxides Ti(OR)₄ arepreferred, more preferably those derived from alcohols ROH having 1 to 8carbon atoms, as for example methanol, ethanol, isopropanol, n-propanol,n-butanol, isobutanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol,and n-octanol, preferably methanol, ethanol, isopropanol, n-propanol,n-butanol, and tert-butanol, more preferably isopropanol and n-butanol.

If at all, these catalysts are employed in an amount of 0.001 to 5 wt.%, preferably 0.005 to 1 wt. %, based on the overall weight of thereactants.

The polyaddition reaction for preparing the polyurethane formulation maytake place with particular preference in the presence of cesium salts,as described in DE 10161156. Preferred cesium salts are compounds inwhich the following anions are employed: F—, Cl—, ClO—, ClO₃—, ClO₄—,Br—, I—, IO₃, CN—, OCN—, NO₂—, NO₃—, HCO₃—, CO₃ ²—, S²—, SH—, HSO₃—, SO₃²—, HSO₄—, SO₄ ²—, S₂O₂ ²—, S₂O₄ ²—, S₂O₅ ²—, S₂O₆ ²—, S₂O₇ ², S₂O₈ ²—,H₂PO₂—, H₂PO₄—, HPO₄ ²—, PO₄ ³—, P₂O₇ ⁴—, (OC_(n)H_(2n+1))—,(C_(n)H_(2n−1)O₂)—, (C_(n)H_(2n-3)O₂)—, and (C_(n+1)H_(2n-2)O₄ ²)—, nstanding for the numbers 1 to 20.

Particularly preferred compounds are cesium carboxylates in which theanion conforms to the formula (C_(n)H_(2n−1)O₂)— or(C_(n+1)H_(2n+2)O₄)²— where n is 1 to 20. Especially preferred cesiumsalts have monocarboxylate anions of the general formula(C_(n)H_(2n+1)O₂)— where n stands for the numbers 1 to 20. Particularmention may be made here of formate, acetate, propionate, hexanoate, and2-ethylhexanoate.

The cesium salts are used in amounts of 0.01 to 10 mmol of cesium saltper kg of solvent-free reaction mixture. They are preferably used inamounts of 0.05 to 2 mmol of cesium salt per kg of solvent-free reactionmixture.

The cesium salts can be added to the reaction mixture in solid form, butpreferably in dissolved form. Suitable solvents are polar, aproticsolvents or else protic solvents. Particularly suitable besides waterare also alcohols; especially suitable are polyols, such as are alsoused as synthesis units for polyurethanes, such as ethane-, propane-,and butanediols, for example. The use of the cesium salts makes itpossible to carry out the polyaddition reaction under the customaryconditions.

Addition to the reaction mixture may take place by any desired methods.Thus, for example, it is possible to admix the catalyst for optionalconcomitant use either to the polyisocyanate component (A), (B) and/orto the component (C) before the beginning of the actual reaction. It isalso possible to add the catalyst to the reaction mixture at any timeduring the reaction.

In one preferred embodiment of the present invention, components (B) and(C) are bonded predominantly by urethane groups, whereas the bonding byallophanate groups is to make up the smaller part.

Relative to the hydroxyl groups reacted with an isocyanate in components(B) and (C), preferably more than 50 mol % are bonded via urethanegroups, more preferably at least 60 mol %, very preferably at least 66mol %, more particularly at least 75 mol %, especially at least 80 mol%, and even at least 90 mol %.

The reaction conditions are preferably selected, accordingly, so thatless than 10 mol % of the hydroxyl groups in components (B) and (C) arebonded via allophanate groups in the product. This can be achieved forexample by avoiding reaction conditions of the kind described in EP959087 A1 for achieving a high allophanate content.

This can preferably be achieved by selecting, among the statedcatalysts, those which form allophanate groups only to a small degree.

In particular, the formation of allophanate groups can be kept low byholding the reaction temperature, in the presence of a catalyst, at notmore than 90° C., preferably not more than 85° C., and more preferablyat not more than 80° C.

The course of the reaction can be monitored by determining the NCOcontent by means, for example, of titrimetry. When the target NCOcontent has been reached the reaction is terminated. In the case of apurely thermal reaction regime, this can be done, for example, bycooling the reaction mixture to room temperature. Where a catalyst ofthe aforementioned type is used, however, the reaction is generallystopped by adding suitable deactivators. Examples of suitabledeactivators include organic or inorganic acids, the corresponding acidhalides, and alkylating agents. Examples that may be mentioned includephosphoric acid, monochloroacetic acid, dodecylbenzenesulfonic acid,benzoyl chloride, dimethyl sulfate, and, preferably, dibutyl phosphateand also di-2-ethylhexyl phosphate. The deactivators can be used inamounts of 1 to 200 mol %, preferably 20 to 100 mol %, based on themoles of catalyst.

The resultant polyisocyanate mixtures generally have an NCO content ofpreferably 14.0 to 20.0 wt. %, more preferably 15.0 to 19.0 wt. %.

The resulting polyisocyanate mixtures generally have a viscosity at 23°C. of 2.5 to 12 Pas, more preferably 3 to 8 Pas.

In this specification the viscosity is reported, unless indicatedotherwise, at 23° C. in accordance with DIN EN ISO 3219/A.3 in acone/plate system with a shear rate of 1000 s⁻¹.

The process may be carried out optionally in a suitable solvent (D)which is inert toward isocyanate groups. Examples of suitable solventsare the conventional paint solvents known per se, such as ethyl acetate,butyl acetate, ethylene glycol monomethyl or monoethyl ether acetate,1-methoxy-2-propyl acetate, 3-methoxy-n-butyl acetate, acetone,2-butanone, isobutyl methyl ketone, 4-methyl-2-pentanone, cyclohexanone,cyclopentanone, toluene, xylene, chlorobenzene, white spirit, aromaticswith relatively high degrees of substitution, such as are sold, forexample, under the names Solventnaphtha®, Solvesso®, Shellsol®, Isopar®,Nappar® and Diasol®, propylene glycol diacetate, diethylene glycoldimethyl ether, dipropylene glycol dimethyl ether, diethylene glycolethyl and butyl ether acetate, N-methylpyrrolidone, M-ethylpyrrolidone,and N-methylcaprolactam, and also, preferably, carbonic esters orlactones, which are specified in EP-A1 697 424, page 4 lines 4 to 32,more preferably dimethyl carbonate, diethyl carbonate, 1,2-ethylenecarbonate and 1,2-propylene carbonate, lactones such as β-propiolactone,γ-butyrolactone, ε-caprolactone, and ε-methylcaprolactone, or else anydesired mixtures of such solvents.

It is also possible first to prepare the isocyanates without solvent andthen to use a solvent (D) to take up the product thus obtainable.

Based on the total mixture (sum of components (A), (B), and (C)), thesolvent (D) may be present in amounts of 0 to 60 wt. %, preferably inamounts of 0 to 50 wt. %.

The mixtures may be dispersed preferably in water for the purpose ofpreparing aqueous dispersions; with particular preference, the mixturesare mixed into aqueous dispersions.

The polyisocyanate formulation is suitable for modifying aqueous coatingmaterials (paint, protective coatings), for example for wood, woodveneer, paper, board, card, textile, leather, nonwoven, plasticssurfaces, glass, ceramic, mineral building materials such as cementmoldings and fiber cement slabs, metals, or coated metals, adhesive orimpregnating compositions, for coloring, for example, based on aqueousdispersions or solutions with a solids content of 5 to 60 wt. %,preferably from 5 to 50 wt. %. Suitable coating materials include theaqueous dispersions, known per se, of homopolymers and copolymers ofolefinically unsaturated monomers or polyurethanes or else solutions ofnatural substances, such as of casein, for example.

The polyisocyanate formulations may be used as crosslinking componentsin aqueous dispersions.

The polyisocyanate formulations are added to the aqueous coatingmaterials generally in an amount of 1 to 25, preferably from 2.5 to 20wt. %, based on the solids content of the coating material.

The polyisocyanate formulations may be used in one-component coatingcompositions, in the form of polyurethane dispersions, for example, oras a mixture with a hydroxyl-containing binder, as a two-componentpolyurethane coating composition.

They are applied to the substrate in a known manner by means, forexample, of spraying at a rate of 5 to 500 g solids/m².

Suitable dispersions of homopolymers or copolymers of olefinicallyunsaturated monomers are, for example, conventional dispersions ofhomopolymers or copolymers based on vinyl esters of carboxylic acidshaving 2 to 18, preferably 2 to 4, carbon atoms such as vinyl acetate inparticular, if desired with up to 70 wt. %, based on the total amount ofolefinically unsaturated monomers, of other olefinically unsaturatedmonomers, and/or of homopolymers or copolymers of (meth)acrylic estersof alcohols having 1 to 18, preferably 1 to 4, carbon atoms, such asmethyl, ethyl, propyl, n-butyl, hydroxyethyl or hydroxypropyl(meth)acrylates in particular, together if desired with up to 70 wt. %of other olefinically unsaturated monomers, and/or butadiene-styrenecopolymers having a butadiene content of about 20 to 60 wt. %, and/or ofother diene polymers or copolymers such as polybutadiene or copolymersof butadiene with other olefinically unsaturated monomers such asstyrene, acrylonitrile and/or methacrylonitrile, for example, and/oraqueous dispersions of polymers or copolymers of 2-chloro-1,3-butadiene,if desired with other olefinically unsaturated monomers of the typeexemplified above, e.g., those with a chlorine content of about 30 to 40wt. %, in particular a chlorine content of about 36 wt. %.

Preference is given to aqueous dispersions of copolymers of 90 to 99.5wt. % of acrylates or methacrylates of alkanols comprising 1 to 4 carbonatoms and 0.5 to 10 wt. %, based in each case on the copolymer, ofhydroxyalkyl acrylates and methacrylates having 2 to 20 carbon atoms inthe hydroxyalkyl radical, such as hydroxyethyl, hydroxypropyl orhydroxybutyl acrylate or methacrylate. Such dispersions are known per seand can be prepared conventionally by emulsion polymerization (seeHouben-Weyl, Methoden der organischen Chemie, 4th edition, vol. E 20, p.217 ff.).

Suitable aqueous polyurethane dispersions are those of the type knownper se, as described in, for example, U.S. Pat. No. 3,479,310, GB-A1,076,688, U.S. Pat. No. 4,108,814, U.S. Pat. No. 4,092,286, DE-A 2 651505, U.S. Pat. No. 4,190,566, DE-A 2 732 131 or DE-A 2 811 148.

The aqueous dispersions used may comprise the customary auxiliaries andadditives. These include, for example, fillers, such as quartz powder,quartz sand, highly disperse silica, heavy spar, calcium carbonate,chalk, dolomite or talc, which are often used together with suitablewetting agents such as polyphosphates, for example, such as sodiumhexametaphosphate, naphthalenesulfonic acid, ammonium or sodium salts ofpolyacrylic acids, the wetting agents being added generally in amountsof 0.2 to 0.6 wt. %, based on filler.

Further suitable auxiliaries are organic thickeners to be used inamounts, for example, of 0.01 to 1 wt. %, based on the dispersion, suchas cellulose derivatives, alginates, starch or starch derivatives orpolyacrylic acid, or inorganic thickeners to be used in amounts of 0.05to 5 wt. %, based on the dispersion, such as bentonites, for example, ororganic thickeners such as polyurethane thickeners, for example.

Fungicides for preservation may also be added to the dispersions. Theseare employed generally in amounts of 0.02 to 1 wt. %, based on thedispersion. Examples of suitable fungicides are phenol and cresolderivatives and also organotin compounds.

Substrates for impregnation are, for example, synthetic or nonsyntheticfibers and/or nonwovens or woven fabrics thereof.

The mixtures can be dispersed very finely in aqueous dispersions. Theresulting dispersions are very stable on storage. Moreover, less of thewater-emulsifiable polyisocyanate need be added in order to set thedesired properties of the dispersion or to achieve the desiredproperties during application.

The mixtures can of course be admixed with customary auxiliaries andadditives of coatings technology. These include, for example, defoamers,thickeners, leveling assistants, pigments, emulsifiers, dispersingassistants, and also solvents. The desired processing viscosity is setby adding water.

To prepare the dispersions it is sufficient in the majority of cases touse simple emulsifying techniques, for example, with a mechanicalstirrer, or else in many cases simple mixing of the two components byhand, in order to obtain dispersions having very good properties.Naturally it is also possible, however, to employ mixing techniquesinvolving a relatively high shearing energy, such as jet dispersion, forexample.

The coating materials comprising the mixtures may be used in particularas primers, surfacers, pigmented topcoat materials, and clearcoatmaterials in the sector of automotive refinish or the painting oflarge-size vehicles. The coating materials are particularly suitable forapplications where particularly high application reliability, outdoorweathering stability, optical properties, solvent resistance, chemicalresistance, and water resistance are required, such as in automotiverefinishing and the painting of large-size vehicles.

The coating materials comprising the mixtures may be applied by any of awide variety of spraying methods, such as, for example, air-pressure,airless or electrostatic spraying methods using one-component ortwo-component spraying units, or else by spraying, troweling, knifecoating, brushing, rolling, roller coating, flow coating, laminating,in-mold coating or coextrusion.

The coatings are generally dried and cured under normal temperatureconditions, i.e., without heating the coating. Alternatively, themixtures may be used to produce coatings which following application aredried and cured at elevated temperature, e.g., at 40-250° C., preferably40-150° C., and especially at 40 to 100° C.

The examples which follow are intended to illustrate the properties ofthe invention but without restricting it.

EXAMPLES

In this specification, unless indicated otherwise, parts are to beunderstood as meaning parts by weight.

Polyisocyanate A1:

HDI isocyanurate having an NCO content of 22.2% and a viscosity to DINEN ISO 3219/A.3 (October 1994) of 2800 mPa*s at 23° C. (availablecommercially as Basonat® HI 100 from BASF SE, Ludwigshafen).

Polyether C1-1:

Monofunctional polyethylene oxide, prepared starting from methanol andwith potassium hydroxide catalysis, having an OH number of 112(according to DIN 53240, June 2013) and a molecular weight of 500 g/mol.The basic catalyst residues still present were subsequently neutralizedwith acetic acid and the product was desalted. The same procedure alsoremoves potassium acetate that has formed.

Diol (B1-1)

-   -   Thiodyglycol HP (from BASF SE, Ludwigshafen)    -   Diols (comparative)    -   1,5 Pentanediol    -   Diethylene glycol

Inventive examples 1 to 3, comparative examples 4 to 7:

100 g of polyisocyanate A1, the amount of polyether C1-1 specified inthe table, and the amount of the stated diol specified in the table weremixed, heated, and reacted with one another. After 3 hours at 90° C. thereaction was discontinued when the stated NCO content was reached,corresponding to the complete formation of the urethane. Thecorresponding product had a viscosity at 23° C. as reported in thetable.

Poly- ether NCO Polyisocyanate amount Diol content Viscosity Exampleamount (g) (g) amount (g) (%) (mPa · s) 1 100 17.6 2.0 g 15.8 5500thiodiglycol 2 100 17.6 2.5 g 15.0 8200 thiodiglycol 3 100 17.6 3.7 g14.2 14 600   thiodiglycol 4 (comp.) 100 17.6 0 17.0 2950 5 (comp.) 10017.6 3.1 g 14.2 13 200   1,5- pentanediol 6 (comp.) 100 17.6 3.2 g 14.122 500   diethylene glycol 7 (comp.) 100 48.4 0 11.2 3850

Use examples

100 g of Luhydran® S938T (acrylate-based aqueous polyol, availablecommercially from BASF SE, Ludwigshafen, OH number 100 mg KOH/g, 45%strength in water) were mixed with 2.5 g of butyl diglycol acetate and6.7 g of butyl glycol acetate as film-forming assistants. Using 0.9 g ofa 50% strength solution of dimethylethanolamine in water, the pH of themixture was adjusted to 8.5. The application viscosity was adapted using7.8 g of water and 0.52 g of BYK® 340 (from BYK, polymeric fluorodefoamer) defoamer.

The polyisocyanates from the table above were diluted with dipropyleneglycol dimethyl ether to a solids content of 80%.

These polyisocyanate solutions were added, in an amount corresponding to1 NCO to 1 OH of the Luhydran® 5938T, to 45 g of the polyol formulation,and the mixture was stirred by hand at 140 to 180 revolutions per minutewith a wooden spatula for 20 seconds.

A bar coater was then used to draw down films onto card in a wet filmthickness of 150 μm.

After curing had taken place at 60° C. for 30 minutes, the gloss wasdetermined at an angle of 20° using a micro-TRI-gloss p apparatus fromBYK.

Example Gloss (20°) 1 54.6 2 59.4 3 71.8 4 (comparative) 43.8 5(comparative) 51.0 6 (comparative) 56.9 7 (comparative) 49.6

The comparison of inventive examples 1 to 3 with comparative example 4(same amount of polyether) shows a distinct improvement in the glosswhen using the polyisocyanates of the invention.

In examples 3, 5, and 6, the same molar amount of different diols withthe same chain length was used. Here again, a distinct improvement inthe gloss is apparent through use of component (B) in thepolyisocyanates of the invention.

In inventive example 3 and comparative example 7, equal molar amountswere used of OH components, which in comparative example 7 comeexclusively from the polyether, with omission of the component (B) ofthe invention. Here again, a distinct improvement in the gloss isapparent through use of component (B) in the polyisocyanates of theinvention.

1: A water-emulsifiable polyisocyanate, comprising: an polyisocyanate based on at least one (cyclo)aliphatic diisocyanate, a compound comprising at least two two isocyanate-reactive groups and at least one selected from the group consisting of a thioether group (—S—), a selanyl group (—Se—), a sulfoxide group (—S(═O)—), and a sulfone group (—S(═O)₂—), a compound comprising an isocyanate-reactive group and a dispersive group, and optionally a solvent; wherein: the ratio of NCO groups in the polyisocynate to isocyanate-reactive groups in the compound comprising at least two isocyanate groups and at least one group selected from the group consisting of a thioether group (—S—), a selanyl group (—Se—), a sulfoxide group (—S(═O)—), and a sulfone group (S(═O)₂—) and the compound comprising an isocyanate-reactive group and a dispersive group is 5:1 to 100:1, the ethylene oxide group content, calculated as 44 g/mol, based on the sum of the polyisocyanate based on at least one (cyclo)aliphatic diisocyanate, the compound comprising at least two isocyanate groups and at least one group selected from the group consisting of a thioether group (—S—), a selanyl group (—Se—), a sulfoxide group (—S(═O)—), and a sulfone group (—S(═O)₂—) and the compound comprising an isocyanate-reactive group and a dispersive group is at least 12 wt. %, the amount of the compound comprising an isocyanate-reactive group and a dispersive group, based on the polyisocyanate based on at least one (cyclo)aliphatic diisocyanate, is at least 5 and up to 25 wt. %, and the viscosity at 23° C. to DIN EN ISO 3219/A.3 (October 1994) in a cone/plate system with a shear rate of 1000 s⁻¹ is from 2500 mPas to 12 000 mPas. 2: The water-emulsifiable polyisocyanate according to claim 1, wherein the (cyclo)aliphatic diisocyanate is selected from the group consisting of hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, 4,4′-di(isocyanatocyclohexyl)methane, and 2,4′-di(isocyanatocyclohexyl)methane. 3: The water-emulsifiable polyisocyanate according to claim 1, wherein the polyisocyanate is an isocyanurate of 1,6-hexamethylene diisocyanate. 4: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising at least two isocyanate groups and at least one group selected from the group consisting of a thioether group (—S—), a selanyl group (—Se—), a sulfoxide group (—S(═O)—), and a sulfone group (—S(═O)₂—) is represented by Formula B1, B2, B3 or B4:

wherein: R⁴ and R⁵, independently of one another, are each a radical that is optionally substituted with functional groups, aryl, alkyl, aryloxyl, halogen, a heteroatom and/or a heterocycle, the radical being selected from the group consisting of a C₁-C₁₈ alkylene, a C₂-C₁₈ alkylene optionally interrupted by one or more oxygen atoms and/or sulfur atoms, a C₆-C₁₂ arylene, and a C₅-C₁₂ cycloalkyl. 5: The water-emulsifiable polyisocyanate according to claim 4, wherein R⁴ and R⁵, independently of one another, are selected from the group consisting of 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 2-methyl-1,3-propylene, 2-ethyl-1,3-propylene, 2,2-dimethyl-1,3-propylene, 2,2-dimethyl-1,4-butylene, 3-oxa-1,5-pentylene, 3,6-dioxa-1,8-octylene, 3,6,9-trioxa-1,11-undecylene, 1,1-, 1,2-, 1,3- or 1,4-cyclohexylene, 1,2- or 1,3-cyclopentylene, 1,2-, 1,3-, or 1,4-phenylene, and 4,4′-biphenylene. 6: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising at least two isocyanate groups and at least one group selected from the group consisting of a thioether group (—S—), a selanyl group (—Se—), a sulfoxide group (—S(═O)—), and a sulfone group (—S(═O)₁) is selected from the group consisting of 3-thiapentane-1,5-diol (thiodiglycol), 1,5-dimethyl-3-thiapentane-1,5-diol, 1-methyl-3-thiahexane-1,6-diol, 4-thiaheptane-1,7-diol, and 4,4′-dihydroxydiphenyl sulfide. 7: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising an isocyanate-reactive group and a dispersive group comprises a monoalcohol comprising at least 7 ethylene oxide groups. 8: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising an isocyanate-reactive group and a dispersive group is represented by the formula: R¹—O—[—X_(i)—]_(k)—H; wherein: R¹ is a C₁-C₁₈ alkyl, C₂-C₁₈ alkyl optionally interrupted by one or more oxygen atoms and/or sulfur atoms, a C₆-C₁₂ aryl, a C₅-C₁₂ cycloalkyl, or a five- to six-membered heterocycle having oxygen, nitrogen and/or sulfur atoms, k is an integer from 7 to 30, and each X_(i) for i=1 to k, independently of one another, is —CH₂—CH₂—O—. 9: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising an isocyanate-reactive group and a dispersive group is represented by the general formula; RG-R⁶-DG; wherein: RG is at least one isocyanate-reactive group, DG is at least one dispersive group selected from the group consisting of —COOH, —SO₃H, —OPO₃H, —PO₃H, and an thereof which may be associated with any desired counterion, and R⁶ is an aliphatic, cycloaliphatic, or aromatic radical comprising 1 to 20 carbon atoms. 10: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising an isocyanate-reactive group and a dispersive group selected from the group consisting of mercaptoacetic acid, mercaptopropionic acid, thiolactic acid, mercaptosuccinic acid, glycine, iminodiacetic acid, sarcosine, alanine, β-alanine, leucine, isoleucine, aminobutyric acid, hydroxyacetic acid, hydroxypivalic acid, lactic acid, hydroxysuccinic acid, hydroxydecanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, ethylenediaminetriacetic acid, hydroxydodecanoic acid, hydroxyhexadecanoic acid, 12-hydroxystearic acid, aminobenzenesulfonic acids substituted on the ring by alkyl, aminonaphthalenecarboxylic acid, hydroxyethanesulfonic acid, hydroxypropanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid, aminomethanesulfonic acid, taurine, aminopropanesulfonic acid, N-alkyl-substituted aminomethanesulfonic acid, cycloalkyl-substituted aminomethanesulfonic acid, aryl-substituted aminomethanesulfonic acid, N-alkyl-substituted aminopropanesulfonic acid, cycloalkyl-substituted aminopropanesulfonic acid, aryl-substituted aminopropanesulfonic acid, an alkali metal thereof, an alkaline earth metal thereof, and an ammonium salt thereof. 11: The water-emulsifiable polyisocyanate according to claim 1, wherein the compound comprising an isocyanate-reactive group and a dispersive group is a phosphoric ester represented by the formulae (Ia) or (Ib) or a mixture thereof

wherein: R¹⁰ and R¹¹, independently of one another, are each an alkyl. 12: The water-emulsifiable polyisocyanate according to claim 11, wherein R¹⁰ and R¹¹ have the general formula (II): wherein: R¹² is a C₁ to C₂₀ alkyl, n is 0 (zero) or a positive integer from 1 to 20, and each X_(i) for i=1 to n, independently of one another, is selected from the group consisting of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, and —CH(CH₃)—CH₂—O—. 13: A method for coating wood, wood veneer, paper, board, card, textile, leather, nonwoven, plastics surfaces, glass, ceramic, mineral building materials, metals, or coated metals, comprising applying the water-emulsifiable polyisocyanate according to claim 1 to the wood, wood veneer, paper, board, card, textile, leather, nonwoven, plastics surfaces, glass, ceramic, mineral building materials, metals, or coated metals. 14: A method for crosslinking a polymer, comprising: mixing the water-emulsifiable polyisocyanate according to claim 1 to an aqueous polymer dispersion. 